1. Field of the Invention
The present invention generally relates to an exposure balance arrangement for an image fixing device and more particularly to an exposure balance arrangement for selectively eliminating areas of an image having unacceptably high light intensity.
2. Discussion of the Background
Photographic and electronic cameras essentially comprise a light-tight enclosure for enclosing a light sensitive material, a lens or other means for forming an image and an arrangement for controlling the time during which light is permitted to reach the light sensitive material, i.e., a shutter. Oftentimes the camera will further include other elements such as the diaphragm for controlling the amount of light emitted by the lens.
One particular problem with employing a shutter or diaphragm to control the exposure of the light sensitive material is that there may be selective areas within the image formed on the photosensitive material which have a light intensity which is larger than desired. In order to compensate for these areas of high light intensity, at least one of the opening size of the diaphragm or opening time of the shutter is reduced. However, this approach can result in an inappropriate exposure of the overall image such that areas which have light intensities below the selective areas of high light intensity are not exposed sufficiently causing dark prints or the like.
Programmable light control matrix devices have been disclosed, such as by U.S. Pat. No. 4,050,814, wherein individually electrically energizable cells, containing electrooptic material, control a light pattern which is transmitted therethrough to form a changeable photographic mask. However, this arrangement makes no provision for utilizing a matrix of light detectors to sense areas of high light intensity to control the darkening of selective ones of individual cells of the light control matrix device to provide exposure balance.
Additionally, a solid state camera has been disclosed in U.S. Pat. No. 4,589,030 in which an electrooptic mask is employed to selectively activate or deactivate regions thereof to pass or block passage of light in image regions through the mask to a detector array such as a charged couple device array. However, this camera makes no provision for employing the electrooptic mask to prevent passage of light having a light intensity greater than a predetermined level to provide exposure balance.
In the image processing apparatus disclosed by U.S. Pat. No. 4,833,540, a shutter is provided with a number shutter elements which correspond to light reception elements of a light reception surface. A scanning arrangement is arranged to generate a scanning signal at predetermined timing so as to successively cause the shutter elements to open in response to the scanning signal. However, this image processing apparatus makes no provision for employing the shutter elements to selectively block areas of an image having high light intensity to provide exposure balance.
The solid state diaphragm device disclosed by U.S. Pat. No. 4,526,450 is employed in an electronic camera. However, this diaphragm makes no provision for selectively darkening areas of high light intensity to provide exposure balance.